Both Rome, expanding from the West, and the Parthian Kingdom, expanding in the East,
put to end the existence of the Seleucid empire and in the 1st century BC became problematic
neighbours and uneasy rivals in the Near East. From the first contact (c. 92 BC) the diplomatic
iniciative seemed to be on the Parthian side and military activities with the ambitious
Roman generals. From 53 BC onwards the Romans tended to settle the problems in the
East by invasions and warfare, mostly with catastrophical endings, such as Crassus’ defeat
and death at Carrhae and disastrous expedition of Marcus Antonius. The Parthians responded
these acts of aggression by ruinous invading Roman provinces (exploating Roman disarray
in the civil wars), but also with no lasting achievements.
Augustus, by contrast, calculating unsafe hopes and great risks of a heavy conflict
with Parthia decided to solve problems diplomatically. Having used an impressive threat
of his legions, he reached a diplomatic accomodation with two Parthian kings, Phraates
IV and Phraataces (Phraates V), in 20 BC and AD 2, which in formal treatises stated Euphrates
as demarcation line between both empires and a nominal dominance of Rome over
Armenia. Thanks to this aggreement, which was propagated as a military success in Rome.
Augustus had free hands for another political and expansionistic aims in the West, in the
Rhine and Danube regions, where the Princeps saw the priorities of his „global“ imperial
governing and could aquire new lands for Rome.